Needle free medical connector with expanded valve mechanism and method of fluid flow control

ABSTRACT

A needle free medical connector includes a housing with a first port and a second port. The connector also includes a piston element defining a fluid passageway between the first and second ports. The piston element is movable between flow and non-flow positions. The piston element has a compressible section having a variable inner width that forms a part of the flow path through the connector. As the piston is compressed to the flow position, the compressible section self-expands in width thereby maintaining or increasing the volume of the fluid passageway through the connector. The compressible section has a configuration permitting the continuous flow of fluid through its entirety.

INCORPORATION BY REFERENCE

We hereby incorporate by reference U.S. Pat. No. 5,676,346 to Leinsing.

BACKGROUND

The invention relates generally to medical connectors of the type usedin the handling and administration of parenteral fluids, and moreparticularly, to a needle free connector employing a valve mechanismthat compensates for negative fluid displacement, i.e., drawing fluidinto the connector, as the connector returns to its unaccessed statefrom an accessed state.

Within this specification the terms, “negative-bolus effect,”“positive-bolus effect,” and “no-bolus effect” are used to describe theoperating characteristics of medical connectors as the connector returnsto its unaccessed state from an accessed state. “Negative-bolus” effectdescribes the condition during which fluid is drawn into the connectoras the connector returns to its unaccessed state from an accessed state.“Positive-bolus effect” describes the condition during which fluid isexpelled out of the connector as the connector returns to its unaccessedstate from an accessed state. “No-bolus effect” describes the conditionduring which fluid displacement is neutralized and fluid is neitherdrawn into nor expelled out of the connector as the connector returns toits unaccessed state from an accessed state.

Needle free medical connectors for injecting fluid into or removingfluid from an intravenous (“IV”) fluid administration set are well knownand widely used. One conventional type of such a connector includes ahousing having connection ports at both ends. One connection port maycomprise a female Luer port sized to receive a blunt male cannula, suchas a male Luer taper. The other connection port may be located oppositethe first port but in some cases is located at a ninety degree or otherangle to the first port, and comprises a male Luer fitting. In manycases the second port of the connector is permanently connected to IVtubing which in turn is connected to an IV catheter that communicateswith a patient's venous system.

A valve is located within the connector and in most cases uses thehousing of the connector as part of the valve mechanism. When theconnector is accessed, the valve opens an internal fluid passagewaybetween the first and second ports. In some connectors, the internalfluid passageway is defined by the internal boundaries of the connectorhousing; in other connectors it is defined by an internal cannula orhollow spike; and still in others, the internal fluid passageway isdefined by a compressible tubular body that carries the valve mechanism.

Many needle free medical connectors create fluid displacement as theconnector is accessed and unaccessed. As the connector is accessed by ablunt male Luer cannula tip inserted into the inlet or first port of theconnector housing, the valve mechanism is engaged. In some connectors,the blunt cannula tip penetrates a valve device to establish fluidcommunication with the internal fluid flow path of the connector. Inother connectors, the blunt cannula tip displaces a valve device withoutpenetrating it in order to establish fluid communication with the fluidflow path. In either case, the volumetric capacity of the fluid flowpath is often reduced by the insertion of the blunt cannula whenaccessing the connector. Subsequently, when the blunt cannula is removedfrom the connector, the volumetric capacity of the fluid flow pathincreases. This increase in the volumetric capacity may create a partialvacuum or pressure reduction in the fluid flow path that may draw fluidinto the connector from the second or downstream end of the connector.As previously mentioned, the effect of drawing fluid into the connectorin this manner is referred to as a “negative-bolus” effect in that aquantity, or “bolus,” of fluid is drawn into the partial vacuum orreduced pressure location within the connector.

A negative-bolus effect as the connector returns to its unaccessed stateis undesirable to some medical care providers and either a neutral bolusor positive bolus effect is preferred. It is therefore desirable toarrange for a valve mechanism that either does not affect the capacityof the internal fluid passageway through the connector as the connectoris returned to its unaccessed state, or that actually decreases it.

In one approach, the negative-bolus effect may be reduced or eliminatedby clamping the IV tubing between the connector and the IV catheterprior to removal of the blunt cannula from the connector. This preventsthe back flow of fluid through the IV catheter and into the connector.However this is an undesirable approach in that another device, i.e. aclamp, is necessary and the care provider must remember to engage theclamp with the tubing. Furthermore, the use of additional devices addsexpense and causes inconvenience in that they may not be available atthe time needed. Additional steps are also undesirable in that most careproviders are very busy already and would therefore naturally prefer toreduce the number of steps in providing effective care to patientsrather than increase the number.

In another approach, one that disadvantageously also increases thenumber of steps in the administration of medical fluids, the operatorcontinually injects fluid into the connector from the male device whilethe male device is being disengaged from the connector. By continuouslyadding fluid the operator attempts to fill the increasing fluid volumeof the fluid flow path through the connector as the male Luer is beingwithdrawn, thereby reducing the likelihood of a partial vacuum and thusthe likelihood of a negative bolus forming in the fluid flow path.However, this approach is also undesirable in that not only does it adda step but may require some skill in successfully carrying out theprocedure.

The negative-bolus effect may also be reduced by the design of themedical connector. As previously mentioned, some medical connectorsinclude an internal cannula or hollow spike housed inside the connectorbody. The internal cannula or spike is positioned to force open a septumupon depression of the septum onto the internal cannula or spike by ablunt cannula. The internal cannula or spike has an orifice at the topand, upon depression of the septum over the internal cannula or spike,the internal cannula or spike is put directly into fluid communicationwith the blunt cannula. The internal cannula or spike provides agenerally fixed-volume fluid-flow path through the connector. Thus, asthe septum returns to its closed position the partial vacuum formedwithin the connector, if any, is not as large as the partial vacuumformed in a connector having a more volumetrically variable internalfluid passageway. A disadvantage of typical connectors having aninternal cannula or spike is a lower fluid-flow rate caused by the smalllumen in the cannula or spike. Additionally, it has been noted that withthe connector design having a fixedly-mounted internal spike and amovable septum that is pierced by that spike to permit fluid flow, suchpierced septum may be damaged with multiple uses and a leaking connectormay result.

Another connector provides a valve mechanism that includes a flexiblebody within which is located a relatively rigid leaf spring. The housingof the connector includes an internal cannula and upon depression of theflexible body by the introduction of a blunt cannula through a port, theinternal cannula forces the leaves of the leaf spring apart. The leavesin turn force the top of the flexible body apart and open a slitcontained therein. The opening of the slit establishes fluidcommunication between the accessing blunt cannula and the lumen of theinternal cannula. The expanding leaf spring also creates areservoir-type area between the flexible body and the outer wall of theinternal cannula in which fluid is held. As the external blunt cannulais removed from the connector, the leaf spring and reservoir collapseand fluid is forced out of the reservoir and into the internal cannulalumen.

This positive displacement of fluid may result in a positive boluseffect as the valve returns to its unaccessed state. However, the valvemechanism is relatively complex with a leaf spring being incorporatedinto a flexible member which adds some manufacturing concerns as well asat least one additional part; i.e., the leaf spring. Manufacturingconcerns and additional parts can tend to cause expenses to rise, anundesirable effect in the health care industry today where manufacturersstrive to provide effective products at lower costs. Further, thereservoir-type system does not permit continuous flow through the entireexpandable flexible body section. Instead, fluid flows into thereservoir and is retained there until the valve is returned to itsunaccessed state.

Hence, those concerned with the development of medical connectors haverecognized the need for a medical connector having a valve mechanismthat avoids the negative-bolus effect by producing either apositive-bolus effect or a no-bolus effect. The need for a medicalconnector that provides these effects without sacrificing fluid-flowrate or structural simplicity has also been recognized. Further needshave also been recognized such as the need for a medical connector thatis less expensive to manufacture, that is efficient in operation, andthat includes fewer parts. The present invention addresses such needsand others.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the invention is directed to a medicalconnector having a valve mechanism that provides either a positive-boluseffect or a no-bolus effect, upon deactuation of the valve mechanism. Aconnector is provided for controlling the flow of fluid, the connectorhaving an internal fluid passageway by which fluid may flow through theconnector, the connector comprises a housing having a first port and asecond port, the first port being adapted to receive a blunt cannula andthe second port adapted for fluid communication with a fluid conduit,and a movable element positioned within the housing, the movable elementhaving a first position at which the movable element blocks fluid flowthrough the housing and a second position at which the movable elementpermits fluid flow through the housing, the movable element comprising ahead defining a bore forming a part of the fluid passageway through theconnector, the head being configured such that when the movable elementis in the second position, the bore self-opens to permit fluid flow, thehead being further configured such that when the moveable element is inthe first position the bore moves to a closed configuration preventingfluid flow, and a compressible section defining an inner conduit forminga part of the fluid passageway through the connector, the inner conduithaving a width moveable between a first width and a second width, thecompressible section being configured so that when the moveable elementis in the second position the compressible section self-expands so thatthe inner conduit has the second width, the inner conduit being furtherconfigured so that when the moveable element is in the first positionthe inner conduit moves to the first width, wherein the first width issmaller than the second width.

In more detailed aspects, the first and second widths of the innerconduit of the compressible section are selected such that the fluidpassageway has a first volume when the movable element is in the firstposition and a second volume when the movable element is in the secondposition, the second volume being larger than the first volume. Further,the first and second widths of the inner conduit of the compressiblesection are selected such that the fluid passageway has a first volumewhen the movable element is in the first position and a second volumewhen the movable element is in the second position, the second volumebeing approximately the same as the first volume. Also, the innerconduit of the compressible section is configured such that fluid maycontinuously flow through the entire inner conduit when the movableelement is located in the second position.

In other more detailed aspects, the connector further comprises asupport tube having opposing ends, the support tube defining a lumenextending between the opposing ends, one end being in fluidcommunication with the second port and the lumen forming a part of theinternal fluid passageway through the connector. The support tubecomprises a wall, the wall defining a slot providing a fluid pathbetween the exterior of the tube and the lumen. The support tube isconfigured in relation to the moveable element such that, when themovable element is in the second position, the lumen and slot of thesupport tube are positioned, at least in part, within the inner conduitof the compressible section such that fluid may flow through the innerconduit of the compressible section, through the slot, through the lumenof the support tube, and through the second port of the housing.

In yet other more detailed aspects, the inner conduit of thecompressible section has opposing first and second ends, the first endbeing adjacent the bore of the head, and the movable element defines anorifice located at the second end of the inner conduit, the orificeforming part of a flow path extending from the bore, through the innerconduit, and out of the inner conduit through the orifice. Further, thelumen and slot of the support tube extend, at least in part, to alocation outside the inner conduit of the compressible section when themovable element is at the second position, and said flow path furtherextends from the orifice, through the slot, and into the lumen at thelocation outside of the inner conduit.

In further more detailed aspects, the moveable element further comprisesa spring section connected to the compressible section, and said flowpath further extends from the orifice, and into the spring sectionwhereby the spring section provides a portion of the internal fluidpassageway. The spring section is extended when the moveable element isin the first position and when extended, the spring section has a firstinternal volume, and the spring section is compressed when the moveableelement is in the second position and when compressed, the springsection has a second internal volume, the second internal volume of thespring section being greater than the first internal volume of thespring section whereby the internal volume of the portion of the flowpath provided by the spring section is greater when the spring sectionis compressed.

In other features, the housing includes a narrowed region adjacent thefirst port, the head of the movable element being located in thenarrowed region when the movable element is in the first position, thenarrowed region being dimensioned so as to cause the bore of the head toclose. Additionally, the housing includes a constricted region, thecompressible section being located in the constricted region when themovable element is in the first position, the constricted region beingdimensioned so as to cause the width of inner conduit of thecompressible section to move to the first width.

Yet further, the compressible section is connected to the head, and themoveable element further comprises a spring section connected to thecompressible section, the spring section being adapted to urge themovable element to the first position at which the compressible sectionis placed within the constricted region. In a more detailed aspect, thehead, and the compressible section, and the spring section are molded asan integral moveable element.

In additional features, the compressible section comprises a pluralityof relatively flexible membrane elements and a plurality of relativelystiff wall elements, the membrane elements connecting together adjacentedges of the wall elements. Further, the membrane elements are adaptedto fold radially inwardly when the inner conduit has the first width.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an assembled medical connector thatincorporates aspects of the present invention, showing a first portsurrounded by thread elements for receiving a blunt connector and athreaded cuff, and a second port comprising a blunt male connector;

FIG. 2 is an exploded perspective view of the medical connector of FIG.1 showing the three components of the medical connector of thisembodiment, including an upper housing portion, a piston element, and alower housing portion;

FIGS. 3 and 4 are elevational views, at right angles to each other, ofthe piston element shown in FIG. 2;

FIG. 5 is an end view of the self-opening head of the piston element ofFIG. 3 showing its normally-open marquise-shaped bore and having thesame orientation as the piston element of FIG. 3;

FIG. 6 is a perspective view in partial cross section of the pistonelement of FIG. 2 with the section taken across the line marked 6—6,showing the self-expanding inner conduit in its normally expandedcondition;

FIG. 7 is a sectional elevation of the medical connector of FIG. 1,showing the connector in a non-accessed state with the piston element inits first position in which the self-opening bore of the piston head isclosed to fluid flow by the narrowed first port of the housing and thecompressible section has been compressed to its first width by anarrowed region of the housing;

FIG. 8 is an enlarged perspective view of the first port of theconnector of FIG. 1 showing the self-opening head of the piston elementin the first position with the marquise shaped bore closed to fluidflow;

FIG. 9 is a sectional view of the medical connector of FIG. 7, takenacross the line marked 9—9 showing the compressible section in itscompressed configuration;

FIG. 10 is a sectional elevation of the medical connector of FIG. 1,showing the connector in an accessed state with the piston elementhaving been moved to its second position in which the self-opening boreof the piston head has opened to fluid flow and the self-expandingconduit of the compressible section has expanded to its normal“as-molded” state, or second width, for increased internal volume;

FIG. 11 is a sectional view of the medical connector of FIG. 7 takenacross line 11—11 showing the self-expanding conduit of the compressiblesection at its normal “as-molded” state, or second width for increasedinternal volume;

FIG. 12 is a detail view of the portion of FIG. 10 showing in enlargeddetail the interaction of the slot and lumen in the support tube withthe self-expanded inner conduit of the compressible section, and theaction of the spring section on the compressible section;

FIG. 13 is a cross-sectional view of the enlarged details of FIG. 12showing the self-expanding inner conduit at its second width, thesupport tube, the slot in the support tube, and showing in particularorifices existing at the base of the inner conduit that permit fluidflow from all parts of the conduit into the slot of the support tube sothat there is continuous fluid flow through the entire inner conduit;

FIGS. 14 and 15 are schematic depictions of an operational principleutilized by a medical connector that incorporates aspects of the presentinvention; and

FIGS. 16 through 18 are perspective views of the piston element showingalternative configurations of the spring section.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now in detail to the drawings in which like numerals refer tolike or corresponding elements among the several figures, there isillustrated in FIG. 1 a side external view of a medical connector thatincludes various aspects of the present invention. The particularconnector configuration exemplified in the figures is for illustrationpurposes only. The connector may be embodied in different configurationsincluding, but not limited to, Y-connectors, J-loops, T-connectors,tri-connectors, PRN adapters, slip Luers, tubing engagement devices,access pins, vial adapters, blood tube adapters, bag access pins, ventedadapters, and others. The drawings are for illustration purposes only.

FIG. 1 presents an embodiment of a medical connector 20 having a housing22 that is formed of an upper housing portion 24 and a lower housingportion 26. The upper housing portion 24 has a first port 28, that inthis case is a female Luer connector port with thread elements 30located about the exterior. The lower housing portion 26 terminates in asecond port 32 that, in this case, comprises a male Luer connector 34defining a lumen 35 (lumen not visible in FIG. 1) and with a threadedlocking collar 36 (threads not visible in FIG. 1). Together, the upperhousing 24 and the lower housing 26 form the connector housing 22. Thehousing 22 may be molded of a material containing a phosphorescentcolorant to render the connector 20 visible in a darkened room or may beformed of a transparent and/or opaque material.

Turning now to FIG. 2, an exploded, somewhat perspective view of theconnector 20 of FIG. 1 is shown. The connector 20 comprises three partsin this embodiment: the housing 22 (see FIG. 1 for numeral 22) thatcomprises the upper housing portion 24 and the lower housing portion 26.The connector 20 also includes a movable element or piston element 38.As will be described in more detail below, the piston element 38 ismounted over a support tube 40 that is formed as part of the lowerhousing portion 26. In one embodiment, the support tube 40 extendsproximally from the center of the lower housing portion 26 and has aninner lumen 42 extending the length of the tube, and in the wall 44 ofthe tube, a longitudinal slot 46 is formed that may extend the length ofthe tube. In the embodiment shown, the lower housing portion 26 alsoincludes a vent 53 used for the escape or intake of air from or to thehousing during movement of the piston element 38. In another embodiment,there may not be a vent.

The housing of the embodiment shown in FIGS. 1 and 2 includes detailsthat aid in manufacturing and that lower the costs of manufacture. As anexample, the exterior surface of the upper portion 48 of the lowerhousing portion 26 is molded to include a crown shaped outer shell thathas several crown points 50. Although not shown in FIG. 2, the interiorof the lower portion 52 of the upper housing portion 24 is molded toinclude a complementary shaped pattern to the crown-shaped lower housingportion. The crown shapes 50 of the lower housing portion 26 mateclosely with the complementary crown shapes (not shown) of the upperhousing portion 24 thereby facilitating a snap-fit assembly of themedical connector housing. A snap ring 51 is also included in the lowerhousing portion 26 and holds the upper housing portion 24 in place onthe lower housing portion 26 once the upper housing portion has beenforced over the snap ring 51. The geometry of the crown shapes alsoprevents rotation of the upper housing portion 24 with the lower housingportion 26 when they are snapped together. Permanent assembly of theupper housing portion with the lower housing portion may also beachieved by means such as ultrasonic weld geometry, a spin weld,bonding, or by other means in other embodiments. This design has beenfound to result in an efficiently manufactured housing assembly that isaccurately assembled, that is quickly and efficiently snapped into asecure assembly.

Referring now to FIGS. 3 and 4 enlarged views of a resilientlydeformable piston element 38 are presented. The same piston element 38is shown in both views, each rotated at right angles to each other. Thepiston element includes three main sections; a piston head 54, acompressible section 56, and a compressible section or spring section58. The compressible section is located between the head and the spring.The piston element may suitably be molded as one piece from a resilientmaterial such as silicone or rubber.

The piston head 54 includes a top portion 60 that is elliptical in outershape, and a bottom, tapered shoulder section 62 that is circular inplan cross-section. Referring now also to FIG. 5, a marquise-shaped bore64 is formed in the elliptically-shaped top section 60. Located betweenthe head 54 and the shoulder section 62 is an elliptical-conical section61 that assists in causing the marquise-shaped bore to tend to remainopen. For further details on the operation of the piston head, see U.S.Pat. No. 5,676,346 to Leinsing, which is incorporated herein byreference. Although not shown in FIGS. 3, 4, or 5, the compressiblesection 56 includes a self-expanding inner conduit that forms one of theaspects of the invention.

Referring now to FIG. 6, a perspective cross-sectional view of thecompressible section 56 is shown. As can be clearly seen, thecompressible section includes an inner conduit 66 formed by two opposingrelatively stiff wall elements 68 that are connected together by twoopposing relatively flexible membrane elements 70. The interconnectionof the wall elements 68 results in the inner conduit 66 with a width 72.It should be noted that the term “width” is not used herein in arestrictive sense; that is, it is not used to indicate the dimension inany particular direction within the inner conduit. It is used instead ina general sense to indicate the interior cross-sectional opening size ofthe inner conduit measured at right angles to the longitudinal axis ofthe moveable element.

The membrane elements 70 are adapted to fold inwardly when a radiallycompressive force is applied to the compressible section 56. Due to therelative stiffness of the wall elements 68, the length of the innerconduit 66 remains substantially constant under such radiallycompressive force. When the radially compressive force is removed orreduced, the inner conduit 66 is self-expanding and tends to expanduntil it is open, as shown in FIG. 6, under the force provided by theresilient material of the compressible section 56.

It can be noted that the inner conduit shown in FIG. 6 has an unusualopening shape. However, the advantageous nature of this opening shapewill be apparent when later figures are discussed below.

Referring now to FIG. 7, the connector 20 of FIG. 1 is shown in verticalcross-sectional format. It should be noted that the connector depictedin FIG. 7 is in an unaccessed state. That is, no blunt cannula has beeninserted into its first port 28 for fluid communication through theconnector.

The upper housing portion 24 has sections of varying internal diameter.The internal section directly adjacent the first port 28 includes astandard ANSI Luer taper portion 100 that incorporates a very slightinward taper. The center portion 102 has a larger internal diameter thanthe Luer taper portion 100 and is separated from the Luer taper portion100 by a tapered lock portion 104. The bottom portion 106 of the upperhousing portion 24 has a larger internal diameter than the centerportion 102 and is separated from the center portion by a tapered rampportion 108. Thus, in relation to the bottom portion 106, the centerportion 102 represents a constricted region, and, in relation to thecenter portion 102, the Luer taper portion 100 represents a narrowedregion. The bottom portion 106 has an inner diameter large enough topermit the inner conduit 66 to self-expand.

Referring now to both FIGS. 7 and 3, the spring section 58 is shown andwill be discussed in more detail. In the embodiment shown, the springsection 58 is configured to include a plurality of relatively stiffannular wall portions 110 (only two of which are indicated by thenumeral 110 to preserve clarity in the drawings), connected to eachother by relatively flexible annular hinges 112, together forming thespring section. The annular wall portions 110 disposed at the center ofthe spring section have an hourglass shape 113 (see FIG. 3) that permitstheir bending at the center point. The hourglass shape and the hingesresult in compression of the spring 58 in a controlled elastic fashionto assume a bellows-like shape in response to an axially compressiveforce, as will be described in relation to FIG. 10 below.

The inner diameter of the spring section 58 is selected to allowpositioning of the spring over the support tube 42 and the outerdiameter of the spring is selected to allow positioning of the springwithin the housing 22. The spring is easily slidable over the supporttube 42 in the embodiment shown but when a compressive force is appliedto the spring, the support tube prevents the spring from buckling andassists the spring in a controlled change to a bellows-type shape.

In the unaccessed state of the connector 20 as shown in FIG. 7, thespring section 58 of the piston element 38 urges the compressiblesection 56 through the ramp portion 108 of the upper housing portion 24into the relatively constricted center portion 102. The location of thecompressible section 56 in this constricted location causes compressionof the compressible section and the inner conduit, as shown in FIG. 9. Aradially compressive force is applied to the compressible section thatcauses the membrane elements 70 to fold inwardly and the stiff wallelements 68 to move toward each other as shown in FIG. 9, therebysubstantially reducing the width 72 of the inner conduit 66 to a firstcompressed width, that is much less than the second expanded width ofthe inner conduit 66 shown in FIG. 6. Had there been any fluid in theinner conduit 66 when it had its second width, as shown in FIG. 6, most,if not all, of that fluid would be expelled as the inner conduit assumedthe first width shown in FIG. 9.

The cross-sectional view of FIG. 7 shows the interaction of the threeparts of the connector of the embodiment discussed. The upper housingportion 24 includes the first port 28 that comprises a female Luerconnector port with thread elements 30 located about the exterior, andis securely connected to the lower housing portion 26. The lower housingportion 26 includes the second port 32 that comprises the male Luerconnector 34 with a threaded locking collar 36. The internal threads arevisible in FIG. 7. The lower housing portion 26 also includes thesupport tube 40 integrally formed with the lower housing portion. Inthis embodiment, the support tube has a length that results in itslocation somewhat within the first housing portion 24 when the completehousing has been assembled. This feature is also apparent from FIG. 2.

Further, the movable element or piston 38 is shown mounted over thesupport tube and extending to the first port 28 of the upper housingportion 24. The piston head 54 is within the narrowed Luer taper region100 of the first housing portion and this narrowing has caused acompressive force to be exerted against the elliptical portion 60 of thepiston head 54, thereby causing the marquise-shaped bore 64 to beclosed. This closed configuration is more clearly shown in FIG. 8 wherethe top of the piston head can be seen and the closed bore 64 is clearlyseen. It should also be noted that this configuration permits easywiping of the piston head before use. This closed bore 64 blocks thefluid flow through the valve in this unaccessed state.

It should be noted that the fluid volume within the connector 20 in thisunaccessed state is defined by the open portion in the piston head underthe closed bore 64, the inner conduit 66 through the compressiblesection, the lumen 42 of the support tube and the second port 32. It isalso informative to note that the support tube and second port are rigidstructures and their internal volumes do not change with the connectorbeing accessed, as will be discussed below. While the bore 64 of thepiston head may appear to be open in FIG. 7, it is closed. Theparticular orientation of the cross section in FIG. 7 results in themarquise-shaped bore being shown along its length, and thus has theappearance of being open. However, a perspective view of the top of thepiston head, such as that shown in FIG. 8, demonstrates that the bore isclosed.

In further reference to FIG. 7, the spring includes a base 114 that ismounted at the base 116 of the support tube 40. The spring may be heldin place at the base of the support tube by friction, adhesive, or othermeans. For example, in the present embodiment, the movable element 38 isplaced in the lower housing portion 26 with the spring section 58 overthe support tube 40 and the base 114 positioned as shown, and the upperhousing portion 24 is placed over the movable element 38 and secured tothe lower housing portion as described above. Because the dimensions ofthe upper housing portion and the lower housing portion are such thatthere is constant, although limited, axial compressive pressure placedon the movable element 38, the spring section 58 tends to stay inposition as shown. This may be referred to as a pre-load force.Incorporated U.S. Pat. No. 5,676,346 to Leinsing may be referred to forfurther details. Extending proximally from the center of the base 116 isthe support tube 40. Extending distally from the base is the male-Luertaper connector 34 having a lumen 35 that is coaxial with the lumen 42of the support tube 40.

Turning now to FIG. 10, the connector 20 in an accessed state is shown.A blunt cannula 130, which is a male Luer connector in this case, hasbeen inserted into the first port 28 into contact with the top section60 of the piston element head and has moved the piston element so thatthe compressible section 56 is now partially over the support tube 40.The spring 58 is now compressed.

As is described in U.S. Pat. No. 5,676,346 to Leinsing, theconfiguration of the piston head results in the bore 64 of the pistonhead being self-opening. That is, the bore 64 is normally open andradial compressive forces must be applied to the piston head to closethe bore. The elliptical-conical portion 61 (see FIGS. 3 and 4) of thepiston element head 54 also uses the axial force from insertion of themale Luer 130 to facilitate the opening of the bore 64. Thus, when themale cannula 130 presses the piston head into the larger interior of thehousing 22 and radial compressive forces are removed from the pistonhead, the bore 64 self-opens to now permit fluid flow through theconnector 20.

Similarly, the compressible section 56 is configured so that the innerconduit 66 is self-expanding. That is, the inner conduit 66 is normallyat its second width and radial compressive forces must be applied to thecompressible section to close the inner conduit, or to force it to haveits smaller first width. Thus, when the male cannula 130 presses thepiston head into the larger interior of the housing 22, and radialcompressive forces are removed from the compressible section, the innerconduit 66 self-expands to its larger second width that will now permita larger fluid volume within the fluid passageway of the connector 20.This larger width either exactly compensates for the decrease in lengthof the fluid passageway through the connector or adds additional volumeto the fluid passageway. As can be seen by reference to FIG. 10,pressing the male cannula 130 into the connector 20 shortens the lengthof the fluid passageway through the connector from the length in FIG. 7and would otherwise thereby reduce the volume of the fluid flow pathalso. However, the increased width of the inner conduit volumetricallycounteracts this decrease in length. This is discussed in more detailbelow in regard to FIGS. 14 and 15.

In FIG. 10, it is shown that the compressible section 56 and the innerconduit 66 are now located partially over the support tube 40. Thisarrangement can be seen in greater detail in the enlarged diagram ofFIG. 12. The support tube however includes a lumen 42 through whichfluid may flow and a longitudinal slot 46 in the wall 44 of the tubethrough which fluid may continuously flow into and out of the supporttube lumen and into and out of the inner conduit as shown in FIG. 10.Fluid that may reach the spring section will also flow into or out ofthe slot of the support tube so that continuous flow occurs throughoutthe connector when in the accessed state. No reservoirs or dead space ofany nature exist so that each part of the fluid passageway is adaptedfor continuous flow through it.

Turning now also to FIG. 11 in conjunction with FIG. 10, the interactionof the support tube 40, its lumen 42, and its slot 46 with the innerconduit 66 may be seen from another angle. FIG. 11 is a cross sectionalview of FIG. 10, which is a connector in the accessed state. In FIG. 11,a possible orientation of the slot of the support tube with the innerconduit wall is shown. In this configuration, the slot 46 of the supporttube resides against one of the stiff walls 68 of the inner conduit.This particular positioning does not prevent fluid flow through theinner conduit because orifices 132 are provided at the bottom of theinner conduit to provide for fluid flow between the inner conduit andthe proximal portion of the spring section. The enlarged diagram in FIG.13 shows the orifices 132 more clearly. In the accessed state, the pointof connection between the spring section 58 and the compressible section56 may be configured to define the orifices 132 through which thesupport tube 40 protrudes. Thus, at the distal end of the inner conduit66, a plurality of gaps or orifices 132 may be defined between thepiston element 38 and the support tube 40 which collectively provide afluid flow path between all portions of the inner conduit 66 and theproximal section 133 (see FIG. 12) of the spring section 58, from whencefluid may flow into the lumen 42 of the support tube via the slot 46.

Thus, the compressible section 56 is configured so that when theconnector 20 is accessed by a blunt cannula 130, fluid may flowcontinuously through the entire inner conduit 66 without a reservoirbeing developed at any point in which fluid may be trapped, held, orretained. The piston element 38 is configured to provide a larger fluidpassageway width at the location of the compressible section 56 when theconnector is in the accessed state, as shown in FIG. 10, thus increasingthe volume of the fluid passageway or keeping it the same as the volumeof the fluid passageway in the unaccessed state, as shown in FIG. 7.

It will be appreciated that, when the slot 46 of the support tube isoriented so that it is facing one of the membrane elements 70 in FIG.11, fluid may flow directly between the lumen 42 of the tube and theinner conduit 66 via the slot 46 or in parallel with fluid flow throughthe orifices 132.

To briefly reiterate, in the accessed state as shown in FIG. 10, theinternal fluid passageway through the connector 20 is through the boreof the piston element, through the head of the piston element, throughthe entire inner conduit 66, through the lumen 42 of the support tube,and through the second port 32. It will be appreciated that flow may bereversed when fluid is withdrawn through the connector. It should benoted that in comparison to FIG. 7, the internal fluid passageway ofFIG. 10 has been shortened by the amount that the blunt cannula 130 hasentered the first port 28, or, put another way, the amount by which theinner conduit 66 now covers the support tube 40. However, theself-expansion of the inner conduit to a greater width hasvolumetrically compensated for the decrease in length of the internalfluid passageway. Conversely, as the blunt male connector 130 iswithdrawn from the first port 28, the internal fluid passageway throughthe connector will lengthen, but at the same time the width of the innerconduit will decrease. If the decrease in width decreases the volume offluid in the internal fluid passageway of the connector by an amountgreater than the increase in length causes an increase in volume, abolus of fluid may be expelled by the connector 20 through the secondport.

In further detail, the inner conduit will be discussed. Referring toFIGS. 9 and 11, the membrane elements 70 may be adapted to fold inwardlywhen a radially compressive force is applied to the compressiblesection. Due to the relative stiffness of the wall elements 68, thelength 134 of the inner conduit 66 remains substantially constant undersuch radially compressive force. Where the radially compressive force isremoved or reduced, the inner conduit 66 is self-expanding and tends toexpand under the force provided by the resilient material of thecompressible section 56.

In regard to the spring section 58, the piston element 38 resilientlydeforms so as to permit the annular portions 110 to alternatingly deforminwardly and outwardly, while allowing rotation to occur mainly at thehinges 112, as exemplified in FIG. 10. A comparison of the two springsection 58 configurations shown in FIGS. 7 and 10 will reveal that whenin the configuration of FIG. 10, the spring section 58 also contributesto the increased internal fluid passageway through the connectorresulting from insertion of the male Luer into the connector. Becausethe longitudinal slot 46 extends substantially along the entire springsection length in the configuration of FIG. 10, fluid may continuouslyflow within the spaces 59 formed between the spring section and thesupport tube 40 resulting from the action of the hinges 112 duringcompression of the spring section.

Referring to FIG. 7, the spring section 58 is in an extendedconfiguration when the moveable element 38 is in the first position;i.e., the connector 20 has not been accessed by a male Luer. As can beseen, the spring section is located quite close to the support tube 40along its entire length. At this location, the spring section has afirst internal volume. When the connector 20 has been accessed and themoveable element 38 has been located at its second position as shown inFIG. 10, the spring section 58 has been compressed. In compression,parts of the spring section remain close to the support tube 40 whileother parts move outwards forming the spaces 59 indicated in FIG. 10.Taking the internal volume of the spring section, which includes theparts near and the parts farther away from the support tube 40, thespring section has a second internal volume, and that second internalvolume is greater than the first internal volume (extended, oruncompressed, spring section). Because of this configuration and thefact that the slot in the support tube extends into the spring section,the spring section forms a part of the internal fluid passageway throughthe connector. In the embodiment shown, the spring section contributesto a net volume increase of that internal fluid passageway when theconnector is accessed. Conversely, when the connector is unaccessed;i.e., when the male Luer 130 is being withdrawn, the spring section willcollapse to the configuration shown in FIG. 7 thereby contributing to adecrease in the net volume of the internal fluid passageway through theconnector.

It will be appreciated that modifications in the shapes of the springsection are possible. Changes may be made to affect flow rate, restoringforce, spring section return rate, volume, differential volume betweencompression and extension configurations, sealing, piston retention, andacceptance of blunt cannulas. Modifications include changing the numberof annular sections, wall thickness and height, or may include differentconfigurations of the spring section entirely, as exemplified in FIGS.16-18.

The use of the support tube 40 also has another advantage. Because ittakes up volume in the internal fluid passageway by virtue of its size,there is less volume for fluid in that passageway when the connector isnot accessed (shown in FIG. 7). This results in a smaller fluidpassageway in the unaccessed state than might otherwise exist if nosupport tube were present. Because it is rigid, it has a fixed volumethat will not change.

FIGS. 14 and 15 are schematic drawings that present the concept of theadjustment of the volume of the internal fluid passageway through aconnector based on expansion and contraction of a part of thatpassageway. In FIG. 14, a schematic connector 136 is shown that includesan internal fluid passageway 138 having a length 140 linking a firstport 142 with a second port 144. In FIG. 14, the single dashed lineadjacent the first sport 142 is used to indicate the closed bore of thepiston head. Forming part of the fluid passageway 138 is an innerconduit 146 having a first width 148. In FIG. 15, a blunt cannula 150has been inserted into the first port 142 of the connector 136 and hasshortened the internal fluid passageway 138 which now has a length shownby numeral 154. The difference between the length 140 of the internalfluid passageway in FIG. 14 and the length 154 of the internal fluidpassageway in FIG. 15 is shown by numeral 156. If nothing else were tochange, the volume of the internal fluid passageway 138 of FIG. 15 wouldnow be less than that of FIG. 14, and a negative bolus effect could beexpected upon removal of the male cannula 150. However, the width 160 ofthe inner conduit 146 in FIG. 15 has been expanded to be greater thanthe width 148 of the inner conduit of FIG. 14. It will be appreciatedthat, by appropriate selection of the expanded and compressed widths ofthe inner conduit, the volume of the fluid path 138 can be made toincrease, stay the same, or decrease when a blunt cannula is made toaccess the connector 136. Where the volume increases, a positivebolus-effect is created when the cannula is removed from the connector.Where the volume remains the same, a neutral-bolus effect is created,and, where the volume decreases, a negative-bolus effect is created.

Turning now to the operation of the medical connector 20, the connectoris initially in its unaccessed state or closed position as shown in FIG.7. The resiliency of the spring section 58 of the piston element 38causes the piston head 54 to be biased into the narrowed ANSI Luer taperportion 100. The shoulder 62 of the piston head 54 contacts the taperedlock portion 104 of the upper housing portion 24 and controls theposition of the top of the piston head 54 in relation to the edge of thefirst port 28 thus forming a swabable surface therewith. The sharppointed ends of the marquise-shaped bore 64 facilitate a tight seal uponcompression of the bore along its minor axis and by compression of thetop section 60 of the piston head 54 along its major axis.

Just prior to accessing the connector with a male Luer connector at thefirst port 28, the top surface of the piston head 54 and the edge of thefirst port may be cleaned by, for example, passing a sterilizing swabover the smooth surface of the piston head lying flush, slightly below,or slightly above the upper surface of the first port. The connector isthen ready to be accessed by a standard male Luer connector with orwithout a threaded locking collar.

The tip of a male Luer connector is brought into contact with theproximal surface of the top section 60 of the piston head 54. Theapplication of sufficient pressure causes the spring section 58 of thepiston element 38 to axially contract and to compress in a bellows-likeconfiguration so that orifices 132 are defined between the springsection 58 and the support tube 40. As the spring section 58 axiallycontracts, the piston head 54 moves out of the narrowed ANSI Luer taperportion 100 of the upper housing portion 24 and into the center portion102. As the piston head 54 clears the tapered lock portion 104 and ismoved into the center portion 102, the larger internal diameter of thecenter portion allows the top section 60 of the piston head toself-expand and to tend to assume its normal elliptical shape and thesame action allows the bore 64 to tend to self-open to assume itsnormally open marquise-shape bore configuration thereby opening a fluidpassageway through the connector and the piston head 54.

Further, as the spring section 58 contracts under axial pressure of themale Luer tip 130, the compressible section 56 moves in the distaldirection from the constricted center portion 102 of the upper housing24 into the larger diameter bottom portion 106 of the upper housing,allowing the compressible section to self-expand and to assume anexpanded configuration. As the compressible section 56 moves in thedistal direction, the support tube 40 will extend into the inner conduit66.

As the blunt cannula 130 becomes fully inserted in the connector 20, thecompressible section fully self-expands, thereby expanding the width ofthe inner conduit. Flow may now occur through the connector. Theinternal fluid passageway through the connector has expanded in width tovolumetrically compensate for the decrease in length, and fluid flowscontinuously through every part of the internal fluid passageway of theconnector. Additionally, fluid flows through the entire compressiblesection 56 due to the slot 46 in the wall 44 of the support tube 40 andthe orifices 132 that permit fluid flow through the distal end of theinner conduit 66 into the proximal section 133 of the spring section andinto the slot 46.

When the blunt cannula 130 is withdrawn from the connector 20 to allowthe connector to return to the non-accessed state, the restoring forcegenerated by the spring section 58 of the piston element 38 causes thecompressible section 56 to be urged proximally past the ramp section 108into the constricted confines of the center section 102 of the upperhousing portion 24 and thus into the compressed condition where theinner width 72 of the inner conduit decreases to its first width, asshown in FIG. 7. Thus, the volume of the fluid passageway through theconduit may decrease, depending on the selected dimensions of thecompressible section 56 and its inner conduit 66. If so, a bolus offluid that was within the inner conduit will be expelled through thesecond port 32. Simultaneously, the elliptical top portion 60 of thepiston head 54 is guided by the tapered lock section 104 into the ANSILuer taper section 100 where it is once again urged into a narrowedcircular shape to close off the orifice 64 and reestablish a positiveseal against fluid flow through the connector 20.

Thus there has been shown and described a new and useful valve for usein medical connectors that provides a controllable bolus effect.Depending on the expanded and compressed widths selected for the innerconduit 66 of the compressible section in relation to the configurationof the balance of the piston element 38, a positive-bolus,neutral-bolus, or negative-bolus effect can be achieved as the connectoris placed in an unaccessed state from an accessed state.

It will be apparent from the foregoing that while particular embodimentsof the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

What is claimed is:
 1. A connector for controlling the flow of fluid,the connector having an internal fluid passageway by which fluid mayflow through the connector, the connector comprising: a housing having afirst port and a second port, the first port being adapted to receive ablunt cannula and the second port adapted for fluid communication with afluid conduit; and a movable element positioned within the housing, themovable element having a first position at which the movable elementblocks fluid flow through the housing and a second position at which themovable element permits fluid flow through the housing, the movableelement comprising: a head defining a bore forming a part of the fluidpassageway through the connector, the head being configured such thatwhen the movable element is in the second position, the bore self-opensto permit fluid flow, the head being further configured such that whenthe moveable element is in the first position the bore moves to a closedconfiguration preventing fluid flow; a compressible section defining aninner conduit forming a part of the fluid passageway through theconnector, the inner conduit having a width moveable between a firstwidth and a second width, the compressible section being configured sothat when the moveable element is in the second position thecompressible section self-expands so that the inner conduit has thesecond width, the inner conduit being further configured so that whenthe moveable element is in the first position the inner conduit moves tothe first width, wherein the first width is smaller than the secondwidth; a support tube having opposing ends, the support tube defining alumen extending between the opposing ends, one end being in fluidcommunication with the second port and the lumen forming a part of theinternal fluid passageway through the connector; wherein the supporttube comprises a wall, the wall defining a slot providing a fluid pathbetween the exterior of the tube and the lumen.
 2. The connector ofclaim 1, wherein the support tube is configured in relation to themoveable element such that, when the movable element is in the secondposition, the lumen and slot of the support tube are positioned, atleast in part, within the inner conduit of the compressible section suchthat fluid may flow through the inner conduit of the compressiblesection, through the slot, through the lumen of the support tube, andthrough the second port of the housing.
 3. The connector of claim 2wherein: the inner conduit of the compressible section has opposingfirst and second ends, the first end being adjacent the bore of thehead; and the movable element defines an orifice located at the secondend of the inner conduit, the orifice forming part of a flow pathextending from the bore, through the inner conduit, and out of the innerconduit through the orifice.
 4. The connector of claim 3 wherein: thelumen and slot of the support tube extend, at least in part, to alocation outside the inner conduit of the compressible section when themovable element is at the second position; and said flow path furtherextends from the orifice, through the slot, and into the lumen at thelocation outside of the inner conduit.
 5. The connector of claim 3wherein: the moveable element further comprises a spring sectionconnected to the compressible section; and said flow path furtherextends from the orifice, and into the spring section whereby the springsection provides a portion of the internal fluid passageway.
 6. Theconnector of claim 5 wherein: the spring section is extended when themoveable element is in the first position and when extended, the springsection has a first internal volume; and the spring section iscompressed when the moveable element is in the second position and whencompressed, the spring section has a second internal volume, the secondinternal volume of the spring section being greater than the firstinternal volume of the spring section; whereby the internal volume ofthe portion of the flow path provided by the spring section is greaterwhen the spring section is compressed.
 7. A connector for controllingthe flow of fluid, the connector having an internal fluid passageway bywhich fluid may flow through the connector, the connector comprising: ahousing having a first port and a second port, the first port beingadapted to receive a blunt cannula and the second port adapted for fluidcommunication with a fluid conduit; and a movable element positionedwithin the housing, the movable element having a first position at whichthe movable element blocks fluid flow through the housing and a secondposition at which the movable element permits fluid flow through thehousing, the movable element comprising: a head defining a bore forminga part of the fluid passageway through the connector, the head beingconfigured such that when the movable element is in the second position,the bore self-opens to permit fluid flow, the head being furtherconfigured such that when the moveable element is in the first positionthe bore moves to a closed configuration preventing fluid flow; acompressible section defining an inner conduit forming a part of thefluid passageway through the connector, the inner conduit having a widthmoveable between a first width and a second width, the compressiblesection being configured so that when the moveable element is in thesecond position the compressible section self-expands so that the innerconduit has the second width, the inner conduit being further configuredso that when the moveable element is in the first position the innerconduit moves to the first width, wherein the first width is smallerthan the second width; and wherein the inner conduit is configured suchthat fluid may continuously flow through the entire inner conduit whenthe movable element is in the second position; and a support tube havingopposing ends, the support tube defining a lumen extending between theopposing ends, one end being in fluid communication with the second portand the lumen forming a part of the internal fluid passageway throughthe connector; wherein the support tube comprises a wall, the walldefining a slot providing a fluid path between the exterior of the tubeand the lumen.
 8. The connector of claim 7 wherein the support tube isconfigured in relation to the moveable element such that, when themovable element is in the second position, the lumen and slot of thesupport tube are positioned, at least in part, within the inner conduitof the compressible section such that fluid may flow through the innerconduit of the compressible section, through the slot, through the lumenof the support tube, and through the second port of the housing.
 9. Theconnector of claim 8 wherein: the inner conduit of the compressiblesection has opposing first and second ends, the first end being adjacentthe bore of the head; and the movable element defines an orifice locatedat the second end of the inner conduit, the orifice forming part of aflow path extending from the bore, through the inner conduit, and out ofthe inner conduit through the orifice.
 10. The connector of claim 9wherein: the lumen and slot of the support tube extend, at least inpart, to a location outside the inner conduit of the compressiblesection when the movable element is at the second position; and saidflow path further extends from the orifice, through the slot, and intothe lumen at the location outside of the inner conduit.
 11. Theconnector of claim 10 wherein: the moveable element further comprises aspring section connected to the compressible section; and said flow pathfurther extends from the orifice, and into the spring section wherebythe spring section provides a portion of the internal fluid passageway.12. The connector of claim 11 wherein: the spring section is extendedwhen the moveable element is in the first position and when extended,the spring section has a first internal volume; and the spring sectionis compressed when the moveable element is in the second position andwhen compressed, the spring section has a second internal volume, thesecond internal volume of the spring section being greater than thefirst internal volume of the spring section; whereby the internal volumeof the portion of the flow path provided by the spring section isgreater when the spring section is compressed.
 13. A connector forcontrolling the flow of fluid, the connector having an internal fluidpassageway by which fluid may flow through the connector, the connectorcomprising: a housing having a first port and a second port, the firstport being adapted to receive a blunt cannula and the second portadapted for fluid communication with a fluid conduit; a movable elementpositioned within the housing, the movable element having a firstposition at which the movable element blocks fluid flow through thehousing and a second position at which the movable element permits fluidflow through the housing, the movable element comprising: a headdefining a bore forming a part of the fluid passageway through theconnector, the head being configured such that when the movable elementis in the second position, the bore self-opens to permit fluid flow, thehead being further configured such that when the moveable element is inthe first position the bore moves to a closed configuration preventingfluid flow; a compressible section defining an inner conduit forming apart of the fluid passageway through the connector, the inner conduithaving a width moveable between a first width and a second width, thecompressible section being configured so that when the moveable elementis in the second position the compressible section self-expands so thatthe inner conduit has the second width, the inner conduit being furtherconfigured so that when the moveable element is in the first positionthe inner conduit moves to the first width, wherein the first width issmaller than the second width, the inner conduit being configured suchthat fluid may continuously flow through the entire inner conduit whenthe movable element is located in the second position; and a supporttube having a first end and a second end with the second end being influid communication with the second port, the support tube having alumen forming a part of the internal fluid passageway through theconnector, the support tube having a wall that defines the lumen and alongitudinal slot formed through the wall and into communication withthe lumen whereby fluid may flow into and out of the lumen through thelongitudinal slot; wherein the lumen and slot of the support tube arelocated within the inner conduit of the compressible section when themovable element is in the second position whereby fluid may flow throughthe inner conduit of the compressible section, through the slot, throughthe lumen of the support tube, and through the second port of thehousing.
 14. The connector of claim 13 wherein: the inner conduit of thecompressible section has a first end and a second end; and the movableelement also comprises an orifice located at the second end of the innerconduit that provides a flow path between the inner conduit and alocation of the fluid passageway that is outside of the inner conduit.15. The connector of claim 14 wherein: the lumen and slot of the supporttube extend to a location outside the inner conduit of the compressiblesection when the movable element is at the second position; and theorifice provides a flow path between the inner conduit and the slot andthe lumen of the support tube at the location outside of the innerconduit.
 16. The connector of claim 15 wherein: the moveable elementfurther comprises a spring section connected to the compressiblesection, the spring section located over the lumen and slot of thesupport tube that extend to the location outside the inner conduit; andthe orifice provides the flow path through the spring section.
 17. Theconnector of claim 16 wherein: the spring section is extended when themoveable element is in the first position and when extended, the springsection has a first internal volume; and the spring section iscompressed when the moveable element is in the second position and whencompressed, the spring section has a second internal volume, the secondinternal volume of the spring section being greater than the firstinternal volume of the spring section; whereby the internal volume ofthe portion of the flow path provided by the spring section is greaterwhen the spring section is compressed.
 18. The connector of claim 13further comprising a narrowed region adjacent the first port of thehousing at which the head of the movable element is located when themovable element is in the first position, the size of the narrowedregion selected so as to cause the bore of the head to close to preventfluid flow through the fluid passageway of the connector.
 19. Theconnector of claim 13 further comprising a narrowed region adjacent thefirst port of the housing at which the compressible section is locatedwhen the movable element is in the first position, the size of thenarrowed region selected o as to cause the inner conduit of thecompressible section to move to its second width.
 20. The connector ofclaim 19 wherein: the compressible section is connected to the head; andthe moveable element further comprises a spring section connected to thecompressible section, the spring section being adapted to urge themovable element to the first position at which the compressible sectionis placed within the narrowed region.
 21. The connector of claim 20wherein the head, and the compressible section, and the spring sectionare molded as an integral element from a resilient material.
 22. Theconnector of claim 13 wherein the compressible section comprises aplurality of substantially inflexible wall elements and a plurality ofsubstantially flexible membrane elements, the membrane elementsconnecting together adjacent edges of the wall elements.
 23. Theconnector of claim 22 wherein the membrane elements are adapted to foldradially inwardly when the inner conduit has the second width.